Allometric vs. Dynamic Models in the Investigation of Pig Growth

A total of 68 barrows, divided into 4 groups regarding the MHS genotype and feeding regime (intensive and restrictive). Data on muscle and fat growth were obtained by magnetic resonance imaging (MRI). Allometric growth analysis showed that muscle tissue grew proportionally with the increase of live weight; fat grew faster in relation to live weight in all investigated groups of pigs. Significant differences in growth coefficients for fat were found only between feeding groups. The analysis by asymmetric S-function was more informative. Muscle growth pattern significantly differed between the groups of investigated pigs (Nn pigs performed better under intensive feeding than under restrictive feeding regime, while no difference was found between NN pigs from two feeding regimes). The optimal slaughter weight of pigs calculated on the basis of live weight and muscle growth (130 and 126 kg for intensively fed NN and Nn pigs, respectively, and about 114 kg for both genotypes from the restricted group of pigs). Growth patterns of fat differed significantly only between the feeding groups. It appears that asymmetric S-function is more accurate and informative model than a simple allometric function, providing a more robust base for important decisions in fattening of pigs.